static int queue_iso_buffer_fill()

in ohci.c [3373:3427]

• 43 lines of code
• 11 McCabe index (conditional complexity)

static int queue_iso_buffer_fill(struct iso_context *ctx,
				 struct fw_iso_packet *packet,
				 struct fw_iso_buffer *buffer,
				 unsigned long payload)
{
	struct descriptor *d;
	dma_addr_t d_bus, page_bus;
	int page, offset, rest, z, i, length;

	page   = payload >> PAGE_SHIFT;
	offset = payload & ~PAGE_MASK;
	rest   = packet->payload_length;

	/* We need one descriptor for each page in the buffer. */
	z = DIV_ROUND_UP(offset + rest, PAGE_SIZE);

	if (WARN_ON(offset & 3 || rest & 3 || page + z > buffer->page_count))
		return -EFAULT;

	for (i = 0; i < z; i++) {
		d = context_get_descriptors(&ctx->context, 1, &d_bus);
		if (d == NULL)
			return -ENOMEM;

		d->control = cpu_to_le16(DESCRIPTOR_INPUT_MORE |
					 DESCRIPTOR_BRANCH_ALWAYS);
		if (packet->skip && i == 0)
			d->control |= cpu_to_le16(DESCRIPTOR_WAIT);
		if (packet->interrupt && i == z - 1)
			d->control |= cpu_to_le16(DESCRIPTOR_IRQ_ALWAYS);

		if (offset + rest < PAGE_SIZE)
			length = rest;
		else
			length = PAGE_SIZE - offset;
		d->req_count = cpu_to_le16(length);
		d->res_count = d->req_count;
		d->transfer_status = 0;

		page_bus = page_private(buffer->pages[page]);
		d->data_address = cpu_to_le32(page_bus + offset);

		dma_sync_single_range_for_device(ctx->context.ohci->card.device,
						 page_bus, offset, length,
						 DMA_FROM_DEVICE);

		rest -= length;
		offset = 0;
		page++;

		context_append(&ctx->context, d, 1, 0);
	}

	return 0;
}